The
original
TriField ® Meter combines all the features needed for fast, accurate
measurements of electromagnetic fields. It independently measures electric field
and magnetic field, and is properly
scaled
to indicate the full magnitude of currents produced by each type of field inside
a conductive body. As a result, it "sees"
much more than any other electromagnetic pollution meter.
Depending on where the knob is set, the
meter detects either frequency-weighted magnetic fields (two separate scales),
or frequency-weighted electric fields in the ELF and VLF range. It has significant
sensitivity at 100,000 Hz, well past the 17,000 Hz horizontal scan of video
displays. The radio/microwave setting can detect up to three billion Hz (3 GHz),
which lets you gauge radio- wave power, CB and cellular phone equipment, and
many types of radars.
This meter is the only one which combines
magnetic, electric, and radio/microwave detectors in one package, so that the
entire nonionizing electromagnetic spectrum is covered. In addition, the magnetic setting and the electric setting measure
true magnitude, a feature found elsewhere only in more expensive meters. If
you hold the meter in the center of a room and tip it to various angles, the
magnetic reading will stay approximately the same regardless of which way you
tip or rotate it. The electric reading is similar, although the presence of
your body alters the actual electric field, so readings will vary more. The
radio/microwave setting reads the full power of radiowaves when the meter is
pointed toward the source.
Surprisingly, the
standard TriField Meter is one of the least expensive meters available. The few other meters below $200 read only low-frequency
magnetic fields and only in one direction (not true magnitude). The magnetic
section of the TriField meter has three field-detecting coils pointing in the
X, Y, and Z directions. A circuit amplifies these signals and gives them the
proper frequency-weighting (sensitivity increases linearly from 30 Hz to 500
Hz, but with some residual sensitivity up to 100 MHz). A unique network combines
the three coil outputs nonlinearly to approximate a true magnitude. The meter
is sensitive from 0.2 to 100 milligauss full scale at 60 Hz (or 0.1 to 50 milligauss
full scale at 120 Hz, etc.) with a resolution of 0.2 milligauss in the sensitive
range. Accuracy is +/-20% at mid-range. A version with flat frequency response
(instead of linear sensitivity increase) is also available for the same price.
The TriField Meter comes with a one-year warranty
and a 9-volt transistor battery included.
This type of battery lasts about 10 hours (total measurement time). When the
BATTERY TEST reads low, the battery can be replaced with any rectangular 9 volt
transistor or alkaline (which lasts about 50 hours) type. This meter is manufactured
in the USA. TriField is a registered trademark of W.B. Lee.
